The invention relates to a filter, in particular for filtering the lubricating oil in an internal combustion engine.
An oil filter for the cleaning of lubricating oil in the internal combustion engines of motor vehicles is known from the European patent document 03 14 915. This is comprised of a filter housing that is at least approximately upright with a cover which can be screwed onto it; further it includes an annular oil filter cartridge inserted in the filter housing, to which the contaminated oil is conveyed. On the bottomfloor of the oil filter housing, there is a bottom discharge valve which opens up a dischargechannel when the cover is opened and the oil filter cartridge is removed. The valve comprises two springs and a valve plate and is constructed in such a way that even with the oil filter cartridge missing, it closes anyway because of the increasing oil pressure, so that a supply of oil to the motor is also assured when no filter cartridge is inserted.
One disadvantage is, however, that when the filter insert is missing, the unfiltered oil reaches the areas to be lubricated and results in damage to the bearings. The motor can be used without an oil filter cartridge for a short time in emergency operation, however it will not be apparent that no oil filter cartridge is present.